Bleaching process and composition



smscnma rn'oosss comosrrron Ralph E. Oliver, Lockpoi't, N. n, assignor to Lockport Cotton Batting (30., Lockport, N. X.

No Drawing. Application March 31, 194i,

Serial No. 386,083

14 Claims. (c 252-137) This invention relates to the bleaching of cellulose fibers, such as exist in cotton textiles and in cotton and wood pulp for example. Heretofore, halogen containing, bleaching agents, such as sodium and calcium hypochlorites, for example,

have been employed extensively in solutionsto bleach cellulose fibers, but results have not been entirely satisfactory due to the adherence to, or

deposit upon, the cellulose fibers of encrusting materials during the bleaching process. Such deposits are objectionable because they weaken 'cr embrittle the bleached fibers and destroy or erated and a bleached product of better quality obtained by performing the bleaching action with a. halogen containing, bleaching agent in the presence of an inorganic .glucosate which may be coagulated by bi-valent ions so as to form that their action may be re arded' as a state and not a form of matter, an that the action is I apparently physical as well as chemical.

In the manufacture of so called chemical cot-' ton and chemical cellulose from wood pulp where a low ash is of primeimportance, this improved process is particularly advantageous because an analysis of pulp bleached by this improved process shows adecrease of from sixteen to thirtythree percent less ash, apparently through the prevention of the'adherence of encrusting materials to the bleached fibers. I have also found .,that cellulose fibers of any kind which are bleached in the presence of the inorganic beta cause they are 'free from encrusting chemicals or matter. These glucosatesare preferably the insmples of such glucosates which-I have found very satisfactory forv this .purpose and which are glucosates have a better luster and greater bril- "liancy than can be obtained by the bleaching processes heretofore employed, apparently bematerials. Equally satisfactory results are ob 'tained inthe bleaching of chemical wood pulp colloidal particles around theencrusting mineral I obtained by the d P the Qulphate P ess and modifications of the sulphate process knownastheKraft process where the manufac-, ture' ofa strong paper .sheetis required. The

fibers' .bleached"by this improved method have typical of materials of this type are sodium-glucosate, phospho-glucosate, pyro-glucosate and tetra-phospho -glucosateh Glucosates of this type may be coagulated by bi-valent ionsand apparl 'ently form colloidal particles or insoluble hydro philic -gels around the encrustingmineral and crustation'forming. elements in what: may be of cotton tha'tis tobe' fabricated by carding greaterstrength' thanv has heretofore been possible, because they are not 'embrittled by any encrusting- 'scal e'or chemicals, and hence this process'ls'fi'lfio-llarticularly useful for the bleachand garnetting, where fiber strength is important.

p 1 have also discovered that these same inorganic other foreign matter-and holdthe scale :or enaptly termed. delayed. precipitation during the; bleaching process.- Thus, the glucosates convert the materials in the bleaching solutionand. on d the fiberswhich would normally. tend to form,

an encrustation on the fibers, into, nonadherent I suspensoids'which hold the encrusting materials in the form of suspended colloids and remain in' suspension in the liquid bleaching bath. After the bleaching action, the colloids may be sepa.-

rated from the cellulose fibers byfdraining be the bath-with the suspended colloids and washing commonlyencountered in a bleaching bath are calcium, magnesium, silicon, iron, carbonates sulphates and organic materials suchas oils, fats,

waxes; and living organisms; While'theexact H y heta glucosides from which satisfactory inorganic beta glucosatesapparently act as catalysts on the bleaching action and byspeeding up the bleaching. reaction, the time required for a bleaching action is materially decreased. The proportions cf the glucosateto be employed may be varied to' 'some extentpdepending upon the character of the fibers and of the encrusting materials that may be Present, as determined by ionic analysis. Generally, excellent results may be obtained by "usingffrom one to one hundred parts by weight or the-glucosate per million parts of the hypochlorite bleaching solution, but ordinarily, it is unnecessary to use more than twentyfive parts of glucosate permillion parts of are sufliciently identified by these names, but as action 01 these inorganic beta 'glucosates. in in hibiting'the deposits of encrusting materials upon the fibers is not definitely known, it is believed the following formula inwhich R is a hydrocara matter fbfjrcorfd, and byway of, example, the

glucosates may be formed may be represented by bon ra dical depending upon the material from which the glucoside is formed:

Beta glucosldc O CHARCHOH-CHOH-lH-CHOH-CHzOH Glucosates formed from such a glucoside and which are excellent catalysts and inhibiting ma-' terials in the present process are:

Scdium-glucosate CHO R- CH ONa-CHOH-bH- CH ONa' CHzOH Phospho-glucosate O CIEO R- CHOH-CHOII-CH-CHOPzOeNm CHzOH Tetra-phospho-glucosate inc n-ononcnon-oh -onNairioncnion In order to further explain the nature of my discovery, reference may be had to the followingspecific examples in which the discovery is given practical application:

Example A 50 grams of caustic boiled and washed cotton linters treated for three hours with 400 ml. of

cold calcium hypochlorite containing 6 grams.

per litre of active chlorine.

After bleaching the stock was washed free from v active chlorine anddried to bone dry base.

The stock bleached toa brightness of 70 G. E. .(The brightness of a standard magnesia block being. 100 G. E.) v

Ash contents-0.75%.

Example B 50 grams of the same caustic boiled and washed cotton linters treated for three hours with 460 ml. of cold calcium hypochlorite containing 6 grams per litre of active chlorine and entrained in this solution 25 P. P. M; (parts per million) of tetra-phospho-glucosate.

After bleaching, the stock was washed free from active chlorine and dried to bone dry base.

The stock bleached to a brightness of 75 G. E.

Ash contents-0.63%.

Comparison of Results 'A and B Example D 50 grams of the same caustic boiled and washed cotton llnters treated for three hours with 400 ml. of cold calcium hypochlorite containing 6 grams per litre of active chlorine and entrained in this solution 50 P. P. M. (parts per million) of tetra-phospho-glucosate.

After bleaching, the stock was washed free from active chlorine and dried to bone dry base.

Stock bleached to a brightness of '75 G. E.

Ash contents-0.51%.

Comparison of Results C and D Difference in brightness-7%. Difference in ash-30%.

Example E Procedure asin Example D, withan entrainment of 100 P. P. M. (parts per phospho-glucosate.

Stock bleached to a brightness of 75 G. E.

Ash contents-0.52%.

Example F Procedure as in Example D, with an entrainment of 10 P. P. M. (parts per million) of tetraphospho-glucosate.

Stock bleached to a brightness of G. E.

Ash contents0.655%.

Comparison of Examples E and F shows the extremes ofentrainment of tetra-phospho-glucosate for this particular grade of cotton linters.

The amount to be used will vary with different grades of stock to be bleached.

In each example using'tetra-phospho-glucosate the cotton reached a brightness of 70 G. E. in two and one-half hours.

The beta glucosates appear to be irreversible colloids which react with alkali and alkaline earth metals to form insoluble hydrophilic gels.

It will be understood that various changes in the details, materials and steps which have been hereinabove described in order to explain the nature of my invention, may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended claims.

I claim as my invention:

1. An improved method oi. cold bleaching of cellulose fibers which comprises subjecting the material to be bleached to the action at the same time, of a hypochlorite bleaching agent and a preformed inorganic glucosate of the type which will be coagulated by bi-valent ions to form colloidal particles.

2,. An improved method of cold bleaching cellulose fibers in a minimum time interval which comprises subjecting the fibers to a hypochlorite bleaching agent in the presence of a preformed inorganic beta glucosate- I 3. An improved method of cold bleaching cellulose fibers in a minimum time interval which comprises subjecting the fibers to a halogen containing, .bleaching. .compound combined with a member of the group consisting of alkali and alkaline earth metals in the presence of a preformed inorganic beta glucosate.

4. An improved methodof cold bleaching celcomprises subjecting the material to be bleached to the action, at the same time, Ms hypochlorite bleaching agent and a preformed inorganic glucosate capable of coagulation by bi-valent ions to form colloidal alkali metal.

6. An improved methodcf cold bleaching or cellulose fibrous materials which comprises subiecting the materials to bebleached to the action million) of tetraparticles and containing an at the same time in a bleaching bath of a hypochlorite, bleaching agent and preformed tetraphospho-glucosate.

'7. An improved method of cold bleaching of fibers of Vegetable origin which comprises subjecting the fibers to be bleached to a bleaching bath having in solution therein a calcium hypochlorite bleaching agent and preformed tetraphospho-glucosate.

8. The method of cold bleaching of fibers of vegetable origin which comprises subjecting the fibers to be bleached to a bleaching bath, containing a calcium hypochlorite bleaching agent and a preformed inorganic glucosate capable of, coagulation by bi-valent ions to form colloidal particles and combined with a salt of phosphoric acid.

9. A bleaching composition operable for the cold bleaching of cellulose fibers in a manner to give the bleached fibers a good luster, a high brilliancy, and freedom from encrusting materials, which comprises a mixture of a hypochlorite bleaching agent and a preformed agent contaim ing an inorganic beta glucosate and capable of coagulation by bi-valent ions to form colloidal agent combined with a member of the group consisting of alkali and alkaline earth metals, and a preformed agent containing a glucosate combined with an inorganic salt and capable of coagulation by bi-valent ions to form colloidal particles.

11. A bleaching composition operable for cold rials, which comprises, a mixture of a halogen containing bleaching. agent combined with a member of the group consisting ofalkali and alkaline earth metals and a preformed agent containing tetra-phospho-glucosate.

14. A bleaching composition operable for the cold bleaching of cellulose fibers in a manner to give the bleached fibers a good luster, a high brilliancy, and freedom from encrusting materials, which comprises a mixture of a calcium hypochlorite bleaching agent and a preformed agent containing tetra-phospho-glucosate.

RALPH R. OLIVER. 

